The consumable component of modern xerographic laser printers is the toner cartridge. Toner cartridges are similar to ink cartridges used by inkjet printers but contain toner powder that is used to form images on paper. During the printing process, the photoreceptor of the laser printer is positively charged and an electrostatic image is formed on the surface of the photoreceptor. The electrostatic image is formed by discharging portions of the photoreceptor surface to form the image. These portions of the photoreceptor surface are negatively discharged. The toner powder is electrostatically drawn from the cartridge and transferred to paper. Because the toner powder features a positive charge, the particles are drawn to the negatively discharged portions of the photoreceptor, forming a toner image on the photoreceptor surface. The toner powder is repelled from the positively charged portions of the photoreceptor. Following the application of the toner powder, the photoreceptor drum is rolled over a sheet of paper. The sheet of paper is given a negative charge that is stronger than the negative charge of the photoreceptor drum. This allows the toner powder to transfer from the photoreceptor drum to the paper. The toner powder is finally heated, melted, and rolled onto the paper by the fuser.
Toner cartridges are typically very expensive which has led to the emergence of an industry for remanufactured toner cartridges. Remanufactured toner cartridges are recycled original toner cartridges that have undergone a number of quality control processes. Used toner cartridges are disassembled and cleaned before the toner hopper is refilled with toner powder. The toner hopper is sealed to prevent the toner cartridge from leaking during use. The toner cartridge is reassembled following the cleaning, refilling, and sealing processes. A common problem of remanufactured toner cartridges is stripped plastic in threaded screw holes. Repeated disassembly and reassembly of the toner cartridges results in stripped threading in the screw holes. The problem is exacerbated by the vibrations experienced by the toner cartridges during use. Unreliable fasteners can lead to problems with the toner cartridge and the laser printer as well. The present invention seeks to address the aforementioned issue and provide a practical, reliable, and repeatable solution.
Therefore it is the object of the present invention to provide a method for remanufacturing empty laser printer toner cartridges that eliminates stripped plastic screw holes commonly encountered during the remanufacturing process and during use. In the preferred embodiment of the present invention, a machine screw insert is slotted into all plastic screw holes of a toner cartridge hopper shell and waste bin shell. The machine screw is attached to a mandrel and inserted into a hole that is threaded by a tap. Each machine screw insert is adhesively held in place within a plastic screw hole. This allows machine screws to be used during the toner cartridge reassembly process without stripping the plastic threading of the screw holes. After the machine screw inserts have been installed, the toner cartridges may be reliably remanufactured multiple times.